#!/usr/bin/env python3

# -*- coding: utf-8 -*-



__author__ = 'caishoubin'



import asyncio, logging



import aiomysql



def log(sql, args=()):

    logging.info('SQL: %s' % sql)



async def create_pool(loop, **kw):

    logging.info('create database connection pool...')

    global __pool

    __pool = await aiomysql.create_pool(

        host=kw.get('host', 'localhost'),

        port=kw.get('port', 3306),

        user=kw['user'],

        password=kw['password'],

        db=kw['db'],

        charset=kw.get('charset', 'utf8'),

        autocommit=kw.get('autocommit', True),

        maxsize=kw.get('maxsize', 10),

        minsize=kw.get('minsize', 1),

        loop=loop

    )



async def select(sql, args, size=None):

    log(sql, args)

    global __pool

    async with __pool.get() as conn:

        async with conn.cursor(aiomysql.DictCursor) as cur:

            await cur.execute(sql.replace('?', '%s'), args or ())

            if size:

                rs = await cur.fetchmany(size)

            else:

                rs = await cur.fetchall()

        logging.info('rows returned: %s' % len(rs))

        return rs



async def execute(sql, args, autocommit=True):

    log(sql)

    async with __pool.get() as conn:

        if not autocommit:

            await conn.begin()

        try:

            async with conn.cursor(aiomysql.DictCursor) as cur:

                await cur.execute(sql.replace('?', '%s'), args)

                affected = cur.rowcount

            if not autocommit:

                await conn.commit()

        except BaseException as e:

            if not autocommit:

                await conn.rollback()

            raise

        return affected



def create_args_string(num):

    L = []

    for n in range(num):

        L.append('?')

    return ', '.join(L)



class Field(object):



    def __init__(self, name, column_type, primary_key, default):

        self.name = name

        self.column_type = column_type

        self.primary_key = primary_key

        self.default = default



    def __str__(self):

        return '<%s, %s:%s>' % (self.__class__.__name__, self.column_type, self.name)



class StringField(Field):



    def __init__(self, name=None, primary_key=False, default=None, ddl='varchar(100)'):

        super().__init__(name, ddl, primary_key, default)



class BooleanField(Field):



    def __init__(self, name=None, default=False):

        super().__init__(name, 'boolean', False, default)



class IntegerField(Field):



    def __init__(self, name=None, primary_key=False, default=0):

        super().__init__(name, 'bigint', primary_key, default)



class FloatField(Field):



    def __init__(self, name=None, primary_key=False, default=0.0):

        super().__init__(name, 'real', primary_key, default)



class TextField(Field):



    def __init__(self, name=None, default=None):

        super().__init__(name, 'text', False, default)



class ModelMetaclass(type):



    def __new__(cls, name, bases, attrs):

        if name=='Model':

            return type.__new__(cls, name, bases, attrs)

        tableName = attrs.get('__table__', None) or name

        logging.info('found model: %s (table: %s)' % (name, tableName))

        mappings = dict()

        fields = []

        primaryKey = None

        for k, v in attrs.items():

            if isinstance(v, Field):

                logging.info('  found mapping: %s ==> %s' % (k, v))

                mappings[k] = v

                if v.primary_key:

                    # 找到主键:

                    if primaryKey:

                        raise StandardError('Duplicate primary key for field: %s' % k)

                    primaryKey = k

                else:

                    fields.append(k)

        if not primaryKey:

            raise StandardError('Primary key not found.')

        for k in mappings.keys():

            attrs.pop(k)

        escaped_fields = list(map(lambda f: '`%s`' % f, fields))

        attrs['__mappings__'] = mappings # 保存属性和列的映射关系

        attrs['__table__'] = tableName

        attrs['__primary_key__'] = primaryKey # 主键属性名

        attrs['__fields__'] = fields # 除主键外的属性名

        attrs['__select__'] = 'select `%s`, %s from `%s`' % (primaryKey, ', '.join(escaped_fields), tableName)

        attrs['__insert__'] = 'insert into `%s` (%s, `%s`) values (%s)' % (tableName, ', '.join(escaped_fields), primaryKey, create_args_string(len(escaped_fields) + 1))

        attrs['__update__'] = 'update `%s` set %s where `%s`=?' % (tableName, ', '.join(map(lambda f: '`%s`=?' % (mappings.get(f).name or f), fields)), primaryKey)

        attrs['__delete__'] = 'delete from `%s` where `%s`=?' % (tableName, primaryKey)

        return type.__new__(cls, name, bases, attrs)



class Model(dict, metaclass=ModelMetaclass):



    def __init__(self, **kw):

        super(Model, self).__init__(**kw)



    def __getattr__(self, key):

        try:

            return self[key]

        except KeyError:

            raise AttributeError(r"'Model' object has no attribute '%s'" % key)



    def __setattr__(self, key, value):

        self[key] = value



    def getValue(self, key):

        return getattr(self, key, None)



    def getValueOrDefault(self, key):

        value = getattr(self, key, None)

        if value is None:

            field = self.__mappings__[key]

            if field.default is not None:

                value = field.default() if callable(field.default) else field.default

                logging.debug('using default value for %s: %s' % (key, str(value)))

                setattr(self, key, value)

        return value



    @classmethod

    async def findAll(cls, where=None, args=None, **kw):

        ' find objects by where clause. '

        sql = [cls.__select__]

        if where:

            sql.append('where')

            sql.append(where)

        if args is None:

            args = []

        orderBy = kw.get('orderBy', None)

        if orderBy:

            sql.append('order by')

            sql.append(orderBy)

        limit = kw.get('limit', None)

        if limit is not None:

            sql.append('limit')

            if isinstance(limit, int):

                sql.append('?')

                args.append(limit)

            elif isinstance(limit, tuple) and len(limit) == 2:

                sql.append('?, ?')

                args.extend(limit)

            else:

                raise ValueError('Invalid limit value: %s' % str(limit))

        rs = await select(' '.join(sql), args)

        return [cls(**r) for r in rs]



    @classmethod

    async def findNumber(cls, selectField, where=None, args=None):

        ' find number by select and where. '

        sql = ['select %s _num_ from `%s`' % (selectField, cls.__table__)]

        if where:

            sql.append('where')

            sql.append(where)

        rs = await select(' '.join(sql), args, 1)

        if len(rs) == 0:

            return None

        return rs[0]['_num_']



    @classmethod

    async def find(cls, pk):

        ' find object by primary key. '

        rs = await select('%s where `%s`=?' % (cls.__select__, cls.__primary_key__), [pk], 1)

        if len(rs) == 0:

            return None

        return cls(**rs[0])



    async def save(self):

        args = list(map(self.getValueOrDefault, self.__fields__))

        args.append(self.getValueOrDefault(self.__primary_key__))

        rows = await execute(self.__insert__, args)

        if rows != 1:

            logging.warn('failed to insert record: affected rows: %s' % rows)



    async def update(self):

        args = list(map(self.getValue, self.__fields__))

        args.append(self.getValue(self.__primary_key__))

        rows = await execute(self.__update__, args)

        if rows != 1:

            logging.warn('failed to update by primary key: affected rows: %s' % rows)



    async def remove(self):

        args = [self.getValue(self.__primary_key__)]

        rows = await execute(self.__delete__, args)

        if rows != 1:

            logging.warn('failed to remove by primary key: affected rows: %s' % rows)
